Emulsion

An emulsion is formed between two liquids that won’t normally mix, when particles of one become suspended in the other. Everyday examples are milk (an emulsion of dairy fat in water) and mayonnaise (oil in egg yolk). Achieving and maintaining an emulsion are often helped by the addition of an emulsifier, such as the mustard in vinaigrette dressings or the natural lecithin present in egg yolk. An important tip in making any of the sauces that involve emulsions, such as mayonnaise and hollandaise, is to have all your utensils and ingredients at the same (ideally room) temperature.